Do or Die - CTF 8

IHC Blog

Hello and welcome to another write-up! Today, we will be tackling an Intermediate Level Cryotherapy Challenge. Let's get started!

Challenge Details:

CTF Name: Do or Die

Topic: Cryptography

Level: Intermediate

Flag Format: IHC_CTF{}

CTF Link: https://t.me/ctf_invisiblehc/15


Description:

Cryptography is amazing. It is very simple to solve. But sometimes it becomes too difficult. 

This is like a do or die CTF.

Download this file:

https://drive.proton.me/urls/RMFZ3YY4HM#O8EVOmJn8VL8


Solution:

We downloaded the txt file from the given challenge link. When I opened the txt file, I found a cipher text with just two words: 'die' and 'do'. Now, we will decrypt the cipher text using this The Python code.

text = input("Enter the text: ") counter = 0 results = [] while True: if text[counter:counter+2].lower() == "do": results.append("1") counter += 2 elif text[counter:counter+3].lower() == "die": results.append("0") counter += 3 else: break print("".join(results)) 

After converting binary, when I decoded the binary code, we got this text.

Go to this Link: https://drive.proton.me/urls/CHV85RDGPG#ibgRskREPdpv "NeedPass?" Oops. I lost the password.

opening the link, it ask me for a password. After examining the texts, I noticed a special text enclosed in double quotation marks. 
I excitedly used that as the password, and it turned out to be the right one.

Once the link was opened with the password, we obtained a QR code image.

We decoded the QR code using this website:

and got a cipher text. 

After decrypting the cipher text using CyberChef, we obtained another URL:
 
Flag Download Link: https://drive.proton.me/urls/6BX48CJ7ER#1KF3VN91qlwj Need PASSWORD? Do you know leet speak 1337?

This link also requires a password, which we realized might be in leet speak (1337). Converting "PASSWORD" into 1337 language, it becomes "P455W0RD." Using this, we successfully opened the link again. Inside, we found a cipher text in the Flag.txt file,

which was base32 encrypted.
We decrypted it using:

and obtained another cipher in Hex format.
We decrypted the Hex cipher using:

and got a binary code. Finally, we decrypted the binary code using CyberChef, and at last, we Found the Flag:
IHC_CTF{M3G4_C7F_1NV151BL3_H4CK3R5_C0MMUN17Y}

Join Our CTF Channel: